1. Field of the Invention
The invention relates to a method for the adaptive automatic control and adjustment of positioning drives, where optimized parameters are determined from the drive motion, and wherein said parameters are corrected and stored in case of a deviation from parameters stored in data storage memories.
2. Brief Description of the Background of the Invention Including Prior Art
Sets of automatic control parameters, adapted to the task at hand, are frequently required in connection with automatically controlled, position-adjustable drives for performing the various positioning tasks. This holds in particular for drives according to the servo-pneumatic drive principle. The difficulty of the automatic control of servo-pneumatic drives is associated with the non-linear behavior of valves and cylinders and depends on the compressibility of the pressure agent. A non-linear, load-dependent control system results in this case in practical situations. It is known to build so-called self-adaptive automatic control systems for adapting the motion values, predeterminable from the respective differential equations and the corresponding set values, based on a determination decisive and appropriate for the control. Not only is an automatic control performed based on a comparison of the set point value and the actual value for the deviation, but in addition the automatic control parameters, to be coordinated to the respective drive motion, are optimized to achieve shorter driving times according to a self-adaptive process and are stored. This means that the automatic control parameters are predetermined at the first passage run and that the automatic control parameters are determined upon repeated passage runs by a practical optimization at the target point as optimized automatic control parameters and are stored for the next passage run. Such systems are generally designated as adaptive controls. Such an automatic control concept is known from a published paper of Professor Rusterholz presented at the 7th Aachener Fluidtechnisches Kolloquium March 1986, Aachen, Federal Republic of Germany contributions to the art field "Pneumatics", volume 3, pages 159-178, in particular 172. The automatic control parameters are adapted to the actual path parameters according to this known method and are designated as controlled adaption. Dependent on the possible piston positions, the corresponding automatic control parameters are read from a fixed value memory storage of a microcomputer and are entered into the automatic control process. The state of the starting and target position has a decisive influence on the optimum value of the adaptive automatic control parameters in connection with servo-pneumatic drives since, dependent on the position of the movable drive part, the compressed air volume, to be controlled by the valves, can vary substantially in the cylinder pipe. This position dependency is also taken into consideration in this conventional method by furnishing a set of adaptive automatic control parameters from a corresponding fixed value memory storage for each position of the drive part of the servo-pneumatic drive and by correcting said set of adaptive automatic control parameters after the end of the task possibly based on observed automatic control target deviations and by providing said possibly corrected set of parameters for the next similar position task. According to the conventional automatic control methods, various values are employed as characterizing numbers for addressing a specific set of automatic control parameters. The coordination of the parameter set to the stored target position, to the drive path, or to the step number of the machine cycle are known. It is a disadvantage in connection with this known method that taking into consideration, for example, only the piston end position is insufficient in order to achieve optimum piston motions. A particular consideration of non-cyclical positioning sequences does also not find any particular attention in the conventional method illustrated. This and other conventional methods become very problematic where target positions have to be reached by driving from different distances, where the distances of the target positions vary substantially based on the stop, and where the positioning is not performed cyclically, or where the number of the positions to be reached cannot be determined for example, in case of furnishing positions based on a master computer or based on an adaptation of the positioning tasks to data of an image evaluation.
In summary, it can be said that the conventional automatic control methods are either exclusively dependent on position, dependent on stroke or, respectively, dependent on distance or they are set dependent or, respectively, cycle dependent. In this case, the position-dependent automatic control does not take into consideration any path distances, the distance-dependent automatic control does not take into consideration any edge position, for example, in the end stop region, and the cycle-dependent automatic control does not take into consideration any non-cyclical positioning tasks. In case of a non-critical selection of a parameter set by overshooting in the target position, there can occur a dangerous operational state. In order to avoid these conditions, frequently a high automatic controller damping is programmed 1 which, however, when not optimally adapted, will result in clock-cycle losses.